This invention relates to the shapeforming of acrylonitrile polymer aquagel film.
It has been believed that polyacrylonitrile homopolymers cannot be thermoformed in the usual sense of the word. For example, in U.S. Pat. No. 3,380,949 it is stated: "It is known that acrylonitrile polymers including homopolymers and copolymers containing about 90% by weight or more of polymerized acrylonitrile, are not thermoplastic in nature and cannot be formed at elevated temperatures by milling, extrusion, compression molding, drawing, or by other commonly employed operations normally used in the forming of shaped articles from truly thermoplastic materials." Further, in Molecular Reviews, Interscience Publishers, John Wiley and Sons, New York, Volume 3, page 115, copyright 1968, it states:
"Polyacrylonitrile has no thermoplastic properties and for a time was found to be soluble only in aqueous salt solutions or aqueous solutions of mineral acids." PA1 (a) providing acrylonitrile polymer aquagel; PA1 (c) while in said shape, heat-removing at least substantially all of the water from said aquagel film.
It is an object of the present invention to provide shapeformable polyacrylonitrile film and the process for shapeforming the same.
It is a further object of the present invention to provide shapeformable polyacrylonitrile aquagel film and the process for shapeforming the same.